Plate cooling method and apparatus



. NOV. 19, 1940. 4 POWERS 2,221,998

PLATE COOLING METHOD AND APPARATUS Filed Sept. 15, 1938 Fm M T Powq: rs

INVENTOR ATT NEY Patented Nov. 19,1940

UNITED ST TES,

- .PLATE oooLING METHOD AND Ai rARATUs F rank l. Powers, Glen'Cove, N. Application September 15, 1938, Serial No. 230,045

.5 Claiins. (01. 62-170) My invention'relates tothe art of 'photoengraving and particularly to a method and'apparatus for cooling photo-mechanical printing I plates during the process of etching said plates.

The objects of my invention are to provide a-method-and an apparatus for cooling hot-metal plates which will not distort or warp; the plate by-reason of uneven or inadequate cooling and which may be carried out by means of apparatus 1'0 of simpler and less expensive construction than those heretofore in common use. v

'Another objectisto provide a cooler which will serve a double function of not only cooling the plate but of wiping surplus water from the 15 back of the plate as the plate is withdrawn from the cooler, leaving no drops of water on the back of the plate. w

' In the making of photo-mechanical printing plates of copper; or zinc by the process known 20 as photoengraving, it is necessary to heat and to cOQLea h plate many times during the process of etching the design upon a surface thereof. This operation of cooling needs to be done by a method which will accomplish the cooling quick- 25 ly, in order to conserve the time of the operator. In the methods commonly used water is applied to the back or unetched side of the hot plate by laying the plate upon a perforated support and forcing water by pump or otherwise through 30 the openings in the support and into contact with the undersurface of the plate being cooled. Thus a flow of water against the under surface of the hot plate is set up which cools the plate quickly. Unfortunately this flow of water is 35 not always uniform over the entire surface of the plate thus causing the plate to cool unevenly and at different rates in different portions which in turn causes uneven contraction and results in warping the plate. 40 When my new method of cooling is used the plate is brought into contact with a supply of water which is not in motion or in only slight .motion and which is uniformly distributed over the surface of the plate thus resulting in a more 45 even cooling and eliminates warping. Then as the plate is withdrawn from the top of the cooler it is drawn over the surface of the cooler top and surplus water and drops of water are automatically removed from the back of the cooled 50 plate.

Briefly, my new method consists essentially in bringing into contact'with the unetched side of the hot plate a body or pad of Water-absorbent or porous water carrying material, such as 55 sponge, either natural or synthetic, or equivalent material; and by the application of a slight pressure upon the absorbent material causing it to exude a sufficient quantity of the fluid simultaneously against all portidns-of the hot-plate to cool it evenlyand quickly without" warping. To 1 bring about 'thisdesired condition I providean apparatus which is typified in the construc-- tion shown in the accompanying drawing. This form of apparatus is to be understood as ex'em-- plary of the invention andnot'restrictive thereof since the essential conditions may be attained by a'variety of forms of construction. 'In the several figureslike or similar parts are desig nated by similarcharacters. v Ofth-e drawing: 1 I

' Figure 1 isa vertical section of the cooler on amedian'line l-ll of Fig. 2" and Fig; 2 is a-ver-" tical section on the'lin'e 2'- 2of Fig. 1. i I

In thedrawing I is a receptaclefo'r the" coolingfluid, such as water, which may forbohvenience be support'ed by legs, not shown in the drawing. Within-thereceptacle l is a rectan-T gular tray 2- which has turned-up -sidesand car ries within it a mat 3 of water absorbent material such as sponge. This tray is supported near its four corners by pivots 4, one near each corner, which are carried by bell crank lever arms 5, which have their fulcrums 6 attached to the receptacle I, the other arms of the bell crank levers are linked together by the bars I, one on either side of the tray 2. A handle bar 8, which may be an extension of one of the bell crank' lever arms serves to apply manual power to the mechanism to raise and lower the tray 2. The bell crank of which the handle bar 8 is a part, 5 is rigidly attached by key or set screw to the shaft l0 thus causing a similar movement of both of the bell cranks on this shaft whenever handle bar 8 is moved.

Across the top of the receptacle I is a series 40 of bars I l, spaced a convenient distance apart, forms a support for the plate I2 which is to be cooled. While I have shown this support to be a series of bars, I may use a variety of other forms of supports such as strips of metal or perforated sheet metal.

The method of operation is as follows:

The receptacle I is filled with a cooling fluid, such as water, to a level slightly above the top of the mat of absorbent material 3 when it is in its lowered position. This level is shown by the broken line l3.

The hot plate to be cooled is placed upon the bars H and by a movement of the handle bar 8 in the direction of the arrow, the mat of completely saturated water absorbent material 3 is raised from its submerged position until it comes into contact with the under side of the plate l2 thus wetting the plate over its entire area and cooling all parts simultaneously.

By a small additional movement of the lever 8 the absorbent mat 3 may be squeezed against the bars II thus expressing or expelling some additional water against the underside of the plate and so expediting its cooling. By carefully gauging the movement of the lever arm, it is possible for one skilled in the art to cool the plate to the optimum temperature for best re-, sults. This optimum temperature is that degree of heat which will permit the operator to handle the plate through the next succeeding step in the process of etching. If plates are cooled stone cold it requires a longer time to heat them up again and they also retain moisture on their surface longer than they do if they are cooled off only to a point where they can still be handled. Atthis somewhat'elevated temperature any residual film of moisture quickly evaporates from the surface of the plate.

This conserves thetime of the operator and experience has shown that it produces best results.

'As the cooled plate is removed from the cooler the back of the plate is drawn across the upper 1 surface of the partially dewatered layer 3 of abface of the plate while held in a horizontal position, a body of porous material substantially saturated with water and applying pressure to said body of material to cause it to exude a portion of the water therein against the surface of the plate in contact therewith.

2. A cooler for photo-mechanical printing plates characterized by a receptacle for a supply of cooling fluid, means for supporting a plate to be cooled, a layer of sponge-like material beneath said supporting means, and means for raising and lowering said layer with respect to the cooling fluid in said receptacle to bring said sponge-like material into contact with said plate resting upon said supporting means.

3. A cooler for photo-mechanical printing plates including in combination, a receptacle for a cooling fluid, a fluid-pervious support for a plate, a layer of fluid-pervious and fluid-retentive material within said receptacle and beneath said support, and means for raising and lowering said lay-er with respect to the fluid in said receptacle and with said support.

4. A cooler for photo-mechanical printing plates including in combination a receptacle for a cooling fluid, a fluid-pervious support for a plate, a layer of sponge-like material within said receptacle and beneath said support and means for raising and lowering said layer with respect to the fluid in said receptacle and with said support.

5. A cooler for photo-mechanical printing plates including in combination, a receptacle for a cooling fluid, a fluid-pervious support for a plate, a layer of fluid-pervious and fluid-retentive material within said receptacle and beneath said support, and means for alternately lowering said layer into the cooling fluid and raising it against said support thereby expressing cooling fluid from the upper portion of said layer into contact with the plate.

FRANK T. POWERS. 

